The present invention relates to nuclear magnetic resonance (NMR) systems and methods for measuring in vivo receiver sensitivity maps.
Accurate characterization of receiver sensitivity is necessary for performing magnetic resonance (MR), particularly fast MR imaging (parallel MR imaging) with multi-channel coils composed of a plurality of coil elements. During parallel magnetic resonance imaging, different receive coils sample different portions of the k-space concurrently. The data from each coil is transformed or “unfolded” in accordance with its sensitivity in reconstructing the final image. The accuracy of the final image depends on accurate characterization of the sensitivity of the coil. Accurate characterization of coil sensitivity is critical for correction of signal intensity inhomogeneity, and accurate and precise quantification of various parameters using MRI and MRS techniques, such as macromolecule, perfusion, and molecule concentration.